Pellicle for an EUV lithography mask and a method of manufacturing thereof

ABSTRACT

A pellicle for an EUV photo mask includes a first layer; a second layer; and a main layer disposed between the first layer and second layer and including a plurality of nanotubes. At least one of the first layer or the second layer includes a two-dimensional material in which one or more two-dimensional layers are stacked. In one or more of the foregoing and following embodiments, the first layer includes a first two-dimensional material and the second layer includes a second two-dimensional material.

RELATED APPLICATION

This application claims priority of U.S. Provisional Patent ApplicationNo. 63/230,555 filed on Aug. 6, 2021, the entire contents of which areincorporated herein by reference.

BACKGROUND

A pellicle is a thin transparent film stretched over a frame that isglued over one side of a photo mask to protect the photo mask fromdamage, dust and/or moisture. In EUV lithography, a pellicle having ahigh transparency in the EUV wavelength region, a high mechanicalstrength and a low thermal expansion is generally required.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A, 1B and 1C show various view of a pellicle for an EUV photomask in accordance with an embodiment of the present disclosure.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F and 2G show various views of networkmembranes of a pellicle for an EUV photo mask in accordance withembodiments of the present disclosure.

FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, 3I and 3J show various views ofnetwork membranes of a pellicle for an EUV photo mask in accordance withembodiments of the present disclosure.

FIGS. 4A, 4B, 4C, 4D, 4E and 4F show various views of pellicles for anEUV photo mask in accordance with an embodiment of the presentdisclosure.

FIG. 5A shows a manufacturing process of a network membrane and FIG. 5Bshows a flow chart thereof in accordance with an embodiment of thepresent disclosure.

FIG. 6 shows a manufacturing process of a network membrane in accordancewith an embodiment of the present disclosure.

FIGS. 7A and 7B show a cross sectional view and a plan (top) view of oneof the various stages for manufacturing a pellicle for an EUV photo maskin accordance with an embodiment of the present disclosure.

FIGS. 8A and 8B show a cross sectional view and a plan (top) view of oneof the various stages for manufacturing a pellicle for an EUV photo maskin accordance with an embodiment of the present disclosure.

FIGS. 9A and 9B show a cross sectional view and a plan (top) view of oneof the various stages for manufacturing a pellicle for an EUV photo maskin accordance with an embodiment of the present disclosure.

FIGS. 10A and 10B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a pellicle for an EUV photomask in accordance with an embodiment of the present disclosure.

FIGS. 11A and 11B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a pellicle for an EUV photomask in accordance with an embodiment of the present disclosure. FIGS.11C and 11D show cross sectional views of one of the various stages formanufacturing a pellicle for an EUV photo mask in accordance withembodiments of the present disclosure.

FIGS. 12A and 12B show a cross sectional view and a plan (top) view ofone of the various stages for manufacturing a pellicle for an EUV photomask in accordance with an embodiment of the present disclosure.

FIG. 13A shows a flowchart of a method making a semiconductor device,and FIGS. 13B, 13C, 13D and 13E show a sequential manufacturingoperation of a method of making a semiconductor device in accordancewith embodiments of present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity. In the accompanying drawings, some layers/features may beomitted for simplification.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.” Further, inthe following fabrication process, there may be one or more additionaloperations in between the described operations, and the order ofoperations may be changed. In the present disclosure, the phrase “atleast one of A, B and C” means either one of A, B, C, A+B, A+C, B+C orA+B+C, and does not mean one from A, one from B and one from C, unlessotherwise explained. Materials, configurations, structures, operationsand/or dimensions explained with one embodiment can be applied to otherembodiments, and detained description thereof may be omitted.

EUV lithography is one of the crucial techniques for extending Moore'slaw. However, due to wavelength scaling from 193 nm (ArF) to 13.5 nm,the EUV light source suffered from strong power decay due to environmentadsorption. Even though a stepper/scanner chamber is operated undervacuum to prevent the strong EUV adsorption by gas, maintaining a highEUV transmittance from the EUV light source to a wafer is still animportant factor in EUV lithography.

A pellicle generally requires a high transparency and a lowreflectivity. In UV or DUV lithography, the pellicle film is made of atransparent resin film. In EUV lithography, however, a resin based filmwould not be acceptable, and a non-organic material, such as apolysilicon, silicide or metal film, is used.

Carbon nanotubes (CNTs) are one of the materials suitable for a pelliclefor an EUV reflective photo mask, because CNTs have a high EUVtransmittance of more than 96.5%. Generally, a pellicle for an EUVreflective mask requires the following properties: (1) Long life time ina rich hydrogen radical operation environment in an EUV stepper/scanner;(2) Strong mechanical strength to minimize the sagging effect duringvacuum pumping and venting operations; (3) A high or perfect blockingproperty for particles larger than about 20 nm (killer particles); and(4) A good heat dissipation to prevent the pellicle from being burnt outby EUV radiation.

In the present disclosure, a pellicle for an EUV photo mask includes anetwork membrane having a plurality of nanotubes and a two-dimensionalmaterial layer covering the network membrane. Such a pellicle has a highEUV transmittance, improved mechanical strength, blocks killer particlesfrom falling on an EUV mask, and/or has improved durability.

FIGS. 1A, 1B and 1C show an EUV pellicle 10 mounted on an EUV reflectivemask 5 in accordance with an embodiment of the present disclosure. FIG.1A is a cross sectional view in the X direction, FIG. 1B is a crosssectional view in the Y direction, and FIG. 1C is a top (plan) view.

In some embodiments, a pellicle 10 for an EUV reflective mask includes afirst cover layer 20, a second cover layer 30 and a main networkmembrane 100 disposed between the first cover layer 20 and the secondcover layer 30. In some embodiments, the main network layer includes aplurality of nanomaterials, such as nanotubes and/or nano-flakes. Insome embodiments, a support frame 15 is attached to the first coverlayer 20 to maintain a space between the membrane of pellicle and theEUV mask 5 (pattern area) when mounted on the EUV mask 5. One of or bothof the first cover layer 20 and the second cover layer 30 include atwo-dimensional material in which one or more two-dimensional layers arestacked. Here, a “two-dimensional” layer generally refers to one or afew crystalline layers of an atomic matrix or a network having thicknesswithin the range of about 0.1-5 nm, in some embodiments.

The support frame 15 of the pellicle is attached to the surface of theEUV photo mask 5 with an appropriate bonding material. In someembodiments, the bonding material is an adhesive, such as acrylic orsilicon based glue or an A-B cross link type glue. The size of the framestructure is larger than the area of the black borders of the EUV photomask so that the pellicle covers not only the circuit pattern area ofthe photo mask but also the black borders.

In some embodiments, the two-dimensional materials of the first coverlayer 20 and the second cover layer 30 are the same or different fromeach other. In some embodiments, the first cover layer includes a firsttwo-dimensional material and the second cover layer includes a secondtwo-dimensional material.

In some embodiments, the two-dimensional material for the first coverlayer 20 and/or the second cover layer 30 includes at least one of boronnitride (BN), graphene, and/or transition metal dichalcogenides (TMDs),represented by MX₂, where M=Mo, W, Pd, Pt, and/or Hf, and X=S, Se and/orTe. In some embodiments, a TMD is one of MoS₂, MoSe₂, WS₂ or WSe₂.

In some embodiments, a total thickness of each of the first cover layer20 and the second cover layer 30 is in a range from 0.3 nm to 3 nm andis in a range from about 0.5 nm to about 1.5 nm in other embodiments. Insome embodiments, a number of the two-dimensional layers of each of thetwo-dimensional materials of the first and/or second cover layers is 1to about 20, and is 2 to about 10 in other embodiments. When thethickness and/or the number of layers is greater than these ranges, EUVtransmittance of the pellicle 10 may be decreased and when the thicknessand/or the number of layers is smaller than these ranges, mechanicalstrength of the pellicle may be insufficient.

In some embodiments, as shown in FIGS. 1A and 1B, the first cover layer20 and the second cover layer 30 are sealed at the periphery thereof tofully encapsulate the main network membrane 100. In some embodiments,the first cover layer 20 and the second cover layer 30 form a vacuumsealed structure. In some embodiments, a pressure inside the vacuumsealed structure is about 0.01 Pa to about 100 Pa. If the insidepressure is too high, for example, higher than an inside pressure of anEUV lithography apparatus in operation, the pellicle may rupture due tothe pressure difference. In some embodiments, one or more vent holes areformed at the first cover layer 20 and/or the second cover layer 30.

In some embodiments, a protection layer 40 is further disposed over thefirst cover layer 20, the second cover layer 30 and the support frame15, as shown in FIGS. 1A and 1B. In some embodiments, the protectionlayer 40 includes at least one layer of an oxide, such as HfO₂, Al₂O₃,ZrO₂, Y₂O₃, or La₂O₃. In some embodiments, the protection layer 40includes at least one layer of non-oxide compounds, such as B₄C, YN,Si₃N₄, BN, NbN, RuNb, YF₃, TiN, or ZrN. In some embodiments, theprotection layer 40 includes at least one metal layer made of, forexample, Ru, Nb, Y, Sc, Ni, Mo, W, Pt, or Bi. In some embodiments, theprotection layer 40 is a single layer, and in other embodiments, two ormore layers of these materials are used as the protection layer 40. Insome embodiments, a thickness of the protection layer is in a range from0.1 nm to 5 nm, and is in a range from about 0.2 nm to about 2.0 nm inother embodiments. When the thickness of the protection layer 40 isgreater than these ranges, EUV transmittance of the pellicle 10 may bedecreased and when the thickness of the protection layer 40 is smallerthan these ranges, the mechanical strength of the pellicle may beinsufficient.

By using the first and/or second cover layer and/or the protectionlayer, which do not have holes, such as opening and/or spaces greaterthan about 10-20 nm, it is possible to fully block killer particleslarger than about 20 nm from passing through the main network membrane100 and falling on the surface of the EUV mask 5.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F and 2G show various network membranes of apellicle for an EUV photo mask in accordance with embodiments of thepresent disclosure.

In some embodiments, the network membrane 100 includes a plurality ofnanotubes. In some embodiments, the plurality of nanotubes are randomlyarranged to form a network structure. In some embodiments, a diameter ofeach of the plurality of nanotubes is in a range from 0.5 nm to 20 nmand is in a range from about 1 nm to about 10 nm in other embodiments.In some embodiments, a length of each of the plurality of nanotubes isin a range from about 0.5 μm to about 50 μm and is in a range from about1.0 μm to about 20 μm in other embodiments.

In some embodiments, the plurality of nanotubes are carbon nanotubes,boron nitride nanotubes, and/or TMD nanotubes, where TMD is representedby MX₂, where M=Mo, W, Pd, Pt, and/or Hf, and X=S, Se and/or Te. In someembodiments, the plurality of nanotubes are MoS₂ nanotubes, MoSe₂nanotubes, WS₂ nanotubes or WSe₂ nanotubes.

In some embodiments, the plurality of nanotubes include only one type ofnanotubes in terms of material and structure. In some embodiments, theplurality of nanotubes include nanotubes of the same material. In someembodiments, the main network membrane 100 only includes single wallnanotubes 111 as shown in FIG. 2A. In other embodiments, the mainnetwork membrane 100 only includes multiwall (e.g., double wall)nanotubes 113 as shown in FIG. 2B. A multiwall nanotube includes aninner tube and one or more outer tubes coaxially disposed around theinner tube. In some embodiments, the outer tube is movable along theaxial direction with respect to the inner tube and in other embodiments,the outer tube is fixed on the outer surface of the inner tube. In someembodiments, a diameter of each of the single wall nanotubes is in arange from about 0.5 nm to about 5 nm and is in a range from about 1 nmto about 2 nm in other embodiments. In some embodiments, a diameter ofeach of the multiwall nanotubes is in a range from about 3 nm to about20 nm and is in a range from about 5 nm to about 10 nm in otherembodiments.

In some embodiments, the plurality of nanotubes include two or moretypes of nanotubes in terms of material and structure. In someembodiments, the plurality of nanotubes include single wall nanotubesmade of two or more materials (mixture of different material nanotubes).For example, in some embodiments, the plurality of nanotubes include aplurality of first nanotubes and a plurality of second nanotubes made ofdifferent material from the plurality of first nanotubes, and both ofthem are single wall nanotubes.

In some embodiments, the main network layer 100 includes a plurality ofnanotubes 111 which are single wall nanotubes, and a plurality ofnanotubes 113 which are multiwall (e.g., double wall) nanotubes as shownin FIG. 2C. In some embodiments, an amount (weight) of the single wallnanotubes 111 is greater than an amount of the multiwall nanotubes 113.In some embodiments, an amount (weight) of the single wall nanotubes 111is greater than an amount of the multiwall nanotubes 113.

In some embodiments, the plurality of single wall nanotubes 111 are madeof a same material as the plurality of multiwall nanotubes 113. Forexample, the plurality of single wall nanotubes 111 are single wallcarbon nanotubes, and the plurality of multiwall nanotubes are multiwallcarbon nanotubes. In other embodiments, the plurality of single wallnanotubes 111 are made of a different material as the plurality ofmultiwall nanotubes 113. For example, the plurality of single wallnanotubes 111 are single wall TMD nanotubes, and the plurality ofmultiwall nanotubes are multiwall carbon nanotubes. In some embodiments,the plurality of nanotubes are multiple nanotubes made of two or moredifferent materials (mixture of two types of multiwall nanotubes).

In some embodiments, the main network membrane 100 includes a pluralityof nanotubes 111 and a plurality of flakes 121 (nano-flakes) made of atwo-dimensional material in which one or more two-dimensional layers arestacked, as shown in FIGS. 2D-2F.

In some embodiments, the two-dimensional material flakes 121 include atleast one of boron nitride (BN), graphene, and/or transition metaldichalcogenides (TMDs), represented by MX₂, where M=Mo, W, Pd, Pt,and/or Hf, and X=S, Se and/or Te. In some embodiments, a TMD is one ofMoS₂, MoSe₂, WS₂ or WSe₂.

In some embodiments, a thickness of two-dimensional material flakes 121is in a range from 0.3 nm to 3 nm and is in a range from about 0.5 nm toabout 1.5 nm in other embodiments. In some embodiments, a number of thetwo-dimensional layers of two-dimensional material flakes 121 is 1 toabout 20, and is 2 to about 10 in other embodiments. When the thicknessand/or the number of layers is greater than these ranges, EUVtransmittance of the pellicle 10 may be decreased and when the thicknessand/or the number of layers is smaller than these ranges, mechanicalstrength of the pellicle may be insufficient.

In some embodiments, the shape of the two-dimensional material flakes121 is random. In other embodiments, the shape of the two-dimensionalmaterial flakes 121 is triangular or hexagonal. In certain embodiments,the shape of the two-dimensional material flakes 121 is a triangleformed by three atoms or a hexagon formed by six atoms. In someembodiments, a size (area) of each of the two-dimensional materialflakes 121 is in a range from about 10 nm² to about 10 μm² and is in arange from about 100 nm² to about 1 μm² in other embodiments.

In some embodiments, the two-dimensional material flakes 121 areembedded in or mixed with a plurality of single wall nanotubes 111 asshown in FIG. 2D. In some embodiments, the two-dimensional materialflakes 121 are embedded in or mixed with a plurality of multiwallnanotubes 113 as shown in FIG. 2E. In some embodiments, thetwo-dimensional material flakes 121 are embedded in or mixed with aplurality of single wall nanotubes 111 and a plurality of multiwallnanotubes 113, as shown in FIG. 2F.

In some embodiments, an amount (weight) of the two-dimensional materialflakes 121 is in a range from about 5% to about 30% with respect to atotal weight of the network membrane 100, and is in a range from about10% to about 20% in other embodiments. When the amount oftwo-dimensional material flakes is greater than these ranges, the EUVtransmittance of the pellicle 10 may be decreased and when the amount oftwo-dimensional material flakes is smaller than these ranges, themechanical strength of the pellicle may be insufficient.

In some embodiments, the network membrane 100 includes multiwallnanotubes 117 each having an inner tube and one or more outer tubes,where the inner tubes and the outer tubes are made of differentmaterials, as shown in FIG. 2G. In some embodiments, each the multiwallnanotubes 117 include an inner tube formed of carbon nanotubes, boronnitride nanotubes, and/or TMD nanotubes, and a coating layer as theouter tubes. In some embodiments, the coating layer includes one of anoxide, such as HfO₂, Al₂O₃, ZrO₂, Y₂O₃, or La₂O₃; a non-oxide compound,such as B₄C, YN, Si₃N₄, BN, NbN, RuNb, YF₃, TiN, or ZrN; and/or a metal,such as, Ru, Nb, Y, Sc, Ni, Mo, W, Pt, or Bi. In some embodiments, thecoating layer is made of the same material as the protection layer 40.

FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, 3I and 3J show various views ofnetwork membranes of a pellicle for an EUV photo mask in accordance withembodiments of the present disclosure. In some embodiments, the networkmembrane 100 has a single layer structure or a multilayer structure.

In some embodiments, the network membrane 100 has a single layer 110 ofa plurality of single or multi wall nanotubes as shown in FIG. 3A. Insome embodiments, the network membrane 100 has two layers of differenttype nanotubes 110 and 112, as shown in FIG. 3B. The thickness of thelayer 110 and layer 112 are the same or different from each other. Insome embodiments, the network membrane 100 has three layers of nanotubes110, 112 and 114, as shown in FIG. 3C. At least adjacent layers aredifferent types in some embodiments. The thickness of the layers 110,112 and 114 are the same or different from each other. In someembodiments, the network membrane 100 has a single layer 115 of amixture of different type nanotubes, as shown in FIG. 3D.

In some embodiments, the network membrane 100 has a nanotube layer 110and a two-dimensional flake layer 120, as shown in FIGS. 3E and 3F. Thethickness of the layer 110 and layer 120 are the same or different fromeach other. The layer 110 can be a mixed layer 115 as shown in FIG. 3D.In some embodiments, the network membrane 100 has a two-dimensionalflake layer 120 disposed between a first nanotube layer 110 and a secondnanotube layer 112, as shown in FIG. 3G. In some embodiments, the firstand second nanotube layers are of the same type or different types. Insome embodiments, the network membrane 100 has a nanotube layer 110disposed between a first two-dimensional flake layer 120 and a secondtwo-dimensional flake layer 122, as shown in FIG. 3H. In someembodiments, the first and second two-dimensional flake layers are madeof the same material or different materials from each other. In someembodiments, the network membrane 100 has a nanotube layer 110, a firsttwo-layer dimensional flake layer 120 over the nanotube layer 110 and asecond two-dimensional flake layer 122 disposed over the firsttwo-dimensional flake layer 120 as shown in FIG. 3I. In someembodiments, the network membrane 100 has one or more nanotube layers ofthe same type or different types and one or more two-dimensional flakelayers of the same material or different materials. In some embodiments,the network membrane 100 has a single layer 125 of a mixture ofnanotubes and two-dimensional flakes, as shown in FIG. 3J.

FIGS. 4A, 4B, 4C, 4D, 4E and 4F show various views of pellicles for anEUV photo mask in accordance with an embodiment of the presentdisclosure.

FIG. 4A is the same as FIGS. 1A-1C. In some embodiments, a pellicle doesnot include a protection layer as shown in FIG. 4B. In some embodiments,the first cover layer is not used and only the second cover layer 30 isdisposed over the main network membrane 100 as shown in FIG. 4C. In someembodiments, the second cover layer is not used and only the first coverlayer 20 is disposed over the main network membrane 100 as shown in FIG.4D. In some embodiments, the first cover layer is not used and only thesecond cover layer 30 is disposed over the main network membrane 100 anda protection layer 40 is formed on the second cover layer and networkmembrane 100 forming covered network layer 119 as shown in FIG. 4E. Insome embodiments, the second cover layer is not used and only the firstcover layer 30 is disposed over the main network membrane 100 and aprotection layer 40 is formed on the second cover layer and networkmembrane 100 forming covered network layer 119 as shown in FIG. 4F.

FIG. 5A shows a manufacturing process of a network membrane and FIG. 5Bshows a flow chart thereof in accordance with an embodiment of thepresent disclosure.

In some embodiments, nanotubes are dispersed in a solution as shown inFIG. 5A. In some embodiments, nanotubes are carbon nanotubes formed byvarious methods, such as arc-discharge, laser ablation or chemical vapordeposition (CVD) methods. Similarly, BN nanotubes and TMD nanotubes arealso formed by a CVD process. The solution is a solvent including wateror an organic solvent such as sodium dodecyl sulfate (SDS). Thenanotubes are one type or two or more types of nanotubes (materialand/or wall structure).

As shown in FIG. 5A, a support membrane is placed between a chamber or acylinder in which the nanotube dispersed solution is disposed and avacuum chamber. In some embodiments, the support membrane is an organicor inorganic porous or mesh material. In some embodiments, the supportmembrane is woven or non-woven fabric. In some embodiments, the supportmembrane has a circular shape in which a pellicle size or a 150 mm×150mm square (the size of an EUV mask) can be placed.

As shown in FIG. 5A, the pressure in the vacuum chamber is reduced sothat a pressure is applied to the solvent in the chamber or cylinder.Since the mesh or pore size of the support membrane is sufficientlysmaller than the size of the nanotubes, the nanotubes are captured bythe support membrane while the solvent passes through the supportmembrane. The support membrane on which the nanotubes are deposited isdetached from the filtration apparatus of FIG. 5A and then is dried. Insome embodiments, the deposition by filtration is repeated so as toobtain a desired thickness of the nanotube network layer as shown inFIG. 5B. In some embodiments, after the deposition of the nanotubes inthe solution, other nanotubes are dispersed in the same or new solutionand the filter-deposition is repeated. In other embodiments, after thenanotubes are dried, another filter-deposition is performed. In therepetition, the same type of nanotubes is used in some embodiments, anddifferent types of nanotubes are used in other embodiments.

FIG. 6 shows a manufacturing process of a network membrane in accordancewith an embodiment of the present disclosure. When the main networkmembrane 100 includes nanotubes and two-dimensional material flakes, thedeposition by filtration for nanotubes and the deposition by filtrationfor the flakes are repeated as shown in FIG. 6 . In some embodiments, amixture of nanotubes and flakes are dispersed in the solvent, and thedeposition by filtration is performed to form a mixed network layer ofnanotubes and two-dimensional material flakes.

Two-dimensional material layer(s) are formed over a substrate by a CVDmethod, and then the deposited layer is peeled off from the substrate.After the two-dimensional material layer is peeled off, the layer iscrushed into flakes in some embodiments.

FIGS. 7A and 7B to 12A and 12B show cross sectional views (the “A”figures) and plan (top) views (the “B” figures) of the various stagesfor manufacturing a pellicle for an EUV photo mask in accordance with anembodiment of the present disclosure. It is understood that additionaloperations can be provided before, during, and after the processes shownby FIGS. 7A-12B, and some of the operations described below can bereplaced or eliminated, for additional embodiments of the method. Theorder of the operations/processes may be interchangeable.

As shown in FIG. 5A, 5B or 6 , a main network membrane 100 is formed ona support membrane 80 by deposition by filtering. The main networkmembrane 100 is then detached from a deposition apparatus, as shown inFIGS. 7A and 7B. Then, as shown in FIGS. 8A and 8B, a first cover layer20 is formed over the main network membrane 100 in some embodiments.

The first cover layer 20, which is a two-dimensional material, is formedby, for example, a CVD method on a substrate, and then the depositedtwo-dimensional layer(s) is peeled off from the substrate. The peeledtwo-dimensional layer(s) is subsequently transferred over the mainnetwork layer 100 formed on the support substrate 80, as shown in FIGS.8A and 8B.

In some embodiments, a TMD layer represented by MX₂ is formed by CVD. Insome embodiments, a MoS₂ layer is formed by CVD using source gases, suchas a Mo(CO)₆ gas, a MoCl₅ gas, and/or a MoOCl₄ gas as a Mo source; and aH₂S gas and/or a dimethyl sulfide gas as a S source. In otherembodiments, a MO₃ gas sublimed from a solid MO₃ or a MoCl₅ sourceand/or S gas is sublimed from a solid S source. Solid sources of Mo andS are placed in a reaction chamber and a carrier gas containing inertgas, such as Ar, N₂ and/or He flows in the reaction chamber. The solidsources are heated to generate gaseous sources by sublimation, and thegenerated gaseous sources react to form MoS₂ molecules. The MoS₂molecules are then deposited on the substrate. The substrate isappropriately heated in some embodiments. In other embodiments, theentire reaction chamber is heated by induction heating. Other TMD layerscan also be formed by CVD using suitable source gases. For example,metal oxides, such as WO₃, PdO₂ and PtO₂ can be used as a sublimationsource for W, Pd and Pt, respectively, and metal compounds, such asW(CO)₆, WF₆, WOCl₄, PtCl₂ and PdCl₂ can also be used as a metal source.In some embodiments, the substrate on which the TMD two-dimensionallayer is formed, includes one of Si (110), γ-Al₂O₃ (110), Ga₂O₃ (010) orMgO (110). In other embodiments, a layer of hexagonal boron nitride(h-BN) or graphene is formed as the first cover layer 20 over asubstrate by CVD. In some embodiments, the substrate includes one of SiC(0001), Si (111), or Ge (111).

Then, as shown in FIGS. 9A and 9B, a support frame 15 is attached to thefirst cover layer 20. In some embodiments, the support frame 15 isformed of one or more layers of crystalline silicon, polysilicon,silicon oxide, silicon nitride, ceramic, metal or organic material. Insome embodiments, as shown in FIG. 9B, the support frame 15 has arectangular (including square) frame shape, which is larger than theblack border area of an EUV mask and smaller than the substrate of theEUV mask.

Next, as shown in FIGS. 10A and 10B, the first cover layer 20, the mainnetwork membrane 100 and the support membrane 80 are cut into arectangular shape having the same size as or slightly larger than thesupport frame 15, and then the support substrate 80 is detached orremoved, in some embodiments. When the support substrate 80 is made ofan organic material, the support substrate 80 is removed by wet etchingusing an organic solvent.

Further, as shown in FIGS. 11A and 11B, a second cover layer 30 isformed over the main network membrane 100. The operations for formingthe second cover layer 30, which is a two-dimensional material, is thesame as or similar to those for the first cover layer 20 as set forthabove. In some embodiments, the first cover layer 20 and the secondcover layer 30 are sealed at the periphery thereof to fully encapsulatethe main network membrane 100.

In some embodiments, the second cover layer 30 has a flange portion atwhich the second cover layer 30 is fixed or bonded to the first coverlayer 20, as shown in FIG. 11C. In other embodiments, the second coverlayer 30 is attached to the sides of the first cover layer 20 and thesupport frame 15 as shown in FIG. 11D.

Further, as shown in FIGS. 12A and 12B, a protection layer 40 is formedover the first cover layer 20, the second cover layer and the supportframe 15. In some embodiments, the protection layer 40 is formed by CVD,physical vapor deposition (PVD) or atomic layer deposition (ALD).

FIG. 13A shows a flowchart of a method of making a semiconductor device,and FIGS. 13B, 13C, 13D and 13E show a sequential manufacturingoperation of the method of making a semiconductor device in accordancewith embodiments of present disclosure. A semiconductor substrate orother suitable substrate to be patterned to form an integrated circuitthereon is provided. In some embodiments, the semiconductor substrateincludes silicon. Alternatively or additionally, the semiconductorsubstrate includes germanium, silicon germanium or other suitablesemiconductor material, such as a Group III-V semiconductor material. AtS801 of FIG. 13A, a target layer to be patterned is formed over thesemiconductor substrate. In certain embodiments, the target layer is thesemiconductor substrate. In some embodiments, the target layer includesa conductive layer, such as a metallic layer or a polysilicon layer; adielectric layer, such as silicon oxide, silicon nitride, SiON, SiOC,SiOCN, SiCN, hafnium oxide, or aluminum oxide; or a semiconductor layer,such as an epitaxially formed semiconductor layer. In some embodiments,the target layer is formed over an underlying structure, such asisolation structures, transistors or wirings. At S802, of FIG. 13A, aphoto resist layer is formed over the target layer, as shown in FIG.13B. The photo resist layer is sensitive to the radiation from theexposing source during a subsequent photolithography exposing process.In the present embodiment, the photo resist layer is sensitive to EUVlight used in the photolithography exposing process. The photo resistlayer may be formed over the target layer by spin-on coating or othersuitable technique. The coated photo resist layer may be further bakedto drive out solvent in the photo resist layer. At S803 of FIG. 13A, thephoto resist layer is patterned using an EUV reflective mask with apellicle as set forth above, as shown in FIG. 13B. The patterning of thephoto resist layer includes performing a photolithography exposingprocess by an EUV exposing system using the EUV mask. During theexposing process, the integrated circuit (IC) design pattern defined onthe EUV mask is imaged to the photo resist layer to form a latentpattern thereon. The patterning of the photo resist layer furtherincludes developing the exposed photo resist layer to form a patternedphoto resist layer having one or more openings. In one embodiment wherethe photo resist layer is a positive tone photo resist layer, theexposed portions of the photo resist layer are removed during thedeveloping process. The patterning of the photo resist layer may furtherinclude other process steps, such as various baking steps at differentstages. For example, a post-exposure-baking (PEB) process may beimplemented after the photolithography exposing process and before thedeveloping process.

At S804 of FIG. 13A, the target layer is patterned utilizing thepatterned photo resist layer as an etching mask, as shown in FIG. 13D.In some embodiments, the patterning the target layer includes applyingan etching process to the target layer using the patterned photo resistlayer as an etch mask. The portions of the target layer exposed withinthe openings of the patterned photo resist layer are etched while theremaining portions are protected from etching. Further, the patternedphoto resist layer may be removed by wet stripping or plasma ashing, asshown in FIG. 13E.

The pellicles according to embodiments of the present disclosure providea higher strength and thermal conductivity (dissipation) as well ashigher EUV transmittance than conventional pellicles. In the foregoingembodiments, two or more types of nanotubes are used as a main networkmembrane to increase the mechanical strength of the pellicle and obtaina high EUV transmittance. Further, a two-dimensional material layer isused as a cover layer (first and/or second cover layers) and/or usedtogether with nanotubes to increase the mechanical strength of apellicle. In addition, by using a two-dimensional material layer and/ora protection layer enclose the main network membrane, it is possible toincrease the mechanical strength of the pellicle and provide a high orperfect blocking property of killer particles. Moreover, the use of thetwo-dimensional material improves heat dissipation to prevent a pelliclefrom being burnt out by EUV radiation in some embodiments.

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

In accordance with one aspect of the present disclosure, a pellicle foran EUV photo mask includes a first layer; a second layer; and a mainlayer disposed between the first layer and second layer and including aplurality of nanotubes. At least one of the first layer or the secondlayer includes a two-dimensional material in which one or moretwo-dimensional layers are stacked. In one or more of the foregoing andfollowing embodiments, the first layer includes a first two-dimensionalmaterial and the second layer includes a second two-dimensionalmaterial. In one or more of the foregoing and following embodiments,each of the first and second two-dimensional materials includes at leastone selected from the group consisting of boron nitride (BN), graphene,MoS₂, MoSe₂, WS₂, and WSe₂. In one or more of the foregoing andfollowing embodiments, the first two-dimensional material is differentfrom the second two-dimensional material. In one or more of theforegoing and following embodiments, a thickness of each of the firstlayer and the second layer is in a range from 0.3 nm to 3 nm. In one ormore of the foregoing and following embodiments, a number of the one ormore two-dimensional layers of each of the first and secondtwo-dimensional materials is 1 to 20. In one or more of the foregoingand following embodiments, the first layer and the second layer aresealed to fully encapsulate the main layer. In one or more of theforegoing and following embodiments, the pellicle further includes aprotection layer disposed over the first layer and the second layer. Inone or more of the foregoing and following embodiments, the protectionlayer includes at least one selected from the group consisting of HfO₂,Al₂O₃, ZrO₂, Y₂O₃, and La₂O₃. In one or more of the foregoing andfollowing embodiments, the protection layer includes at least oneselected from the group consisting of B₄C, YN, Si₃N₄, BN, NbN, RuNb,YF₃, TiN, and ZrN. In one or more of the foregoing and followingembodiments, the protection layer includes a metal layer made of atleast one selected from the group consisting of Ru, Nb, Y, Sc, Ni, Mo,W, Pt, and Bi. In one or more of the foregoing and followingembodiments, a thickness of the protection layer is in a range from 0.1nm to 5 nm. In one or more of the foregoing and following embodiments, adiameter of each of the plurality of nanotubes is in a range from 0.5 nmto 20 nm.

In accordance with another aspect of the present disclosure, a pelliclefor an extreme ultraviolet (EUV) reflective mask includes a first layer;a second layer; and a main layer disposed between the first layer andsecond layer. The main layer includes a plurality of first nanotubes anda plurality of second nanotubes different from the plurality of firstnanotubes. In one or more of the foregoing and following embodiments, atleast one of the first layer or the second layer includes atwo-dimensional material in which one or more two-dimensional layers arestacked. In one or more of the foregoing and following embodiments, theplurality of first nanotubes are single wall nanotubes and the pluralityof second nanotubes are multiwall nanotubes. In one or more of theforegoing and following embodiments, the plurality of first nanotubesare made of a same material as the plurality of second nanotubes. In oneor more of the foregoing and following embodiments, the plurality offirst nanotubes are made of a different material than the plurality ofsecond nanotubes. In one or more of the foregoing and followingembodiments, each of the plurality of first nanotubes and the pluralityof second nanotubes are one or more selected from the group consistingof carbon nanotubes, boron nitride nanotubes, MoS₂ nanotubes, MoSe₂nanotubes, WS₂ nanotubes and WSe₂ nanotubes. In one or more of theforegoing and following embodiments, both the plurality of firstnanotubes and the plurality of second nanotubes are single wallnanotubes. In one or more of the foregoing and following embodiments,both the plurality of first nanotubes and the plurality of secondnanotubes are multiwall nanotubes. In one or more of the foregoing andfollowing embodiments, the plurality of first nanotubes are single wallnanotubes and the plurality of second nanotubes are multiwall nanotubes.

In accordance with another aspect of the present disclosure, a pelliclefor an extreme ultraviolet (EUV) reflective mask includes a first layer;a second layer; and a main layer disposed between the first layer andsecond layer. The main layer includes a plurality of nanotubes and aplurality of flakes comprising two-dimensional material in which one ormore two-dimensional layers are stacked. In one or more of the foregoingand following embodiments, the two-dimensional material includes atleast one selected from the group consisting of boron nitride (BN),graphene, MoS₂, MoSe₂, WS₂, and WSe₂. In one or more of the foregoingand following embodiments, a size of each of the plurality of flakes isin a range from 100 nm² to 100 μm². In one or more of the foregoing andfollowing embodiments, a thickness of each of the plurality of flakes isin a range from 0.3 nm to 3 nm. In one or more of the foregoing andfollowing embodiments, a number of the one or more two-dimensionallayers of each of the plurality of flakes is 1 to 20.

In accordance with another aspect of the present disclosure, a pelliclefor an extreme ultraviolet (EUV) reflective mask includes a firstmembrane; a support frame attached to the first membrane; and a mainlayer disposed over the first layer and including a plurality ofnanotubes. The first membrane includes a two-dimensional material inwhich one or more two-dimensional layers are stacked. In one or more ofthe foregoing and following embodiments, the two-dimensional material ofthe first membranes includes at least one selected from the groupconsisting of boron nitride (BN), graphene, MoS₂, MoSe₂, WS₂, and WSe₂.In one or more of the foregoing and following embodiments, a thicknessof the first membrane is in a range from 0.3 nm to 3 nm. In one or moreof the foregoing and following embodiments, a number of the one or moretwo-dimensional layers of the first membrane is 1 to 20. In one or moreof the foregoing and following embodiments, the first membrane isdisposed between the support frame and the main layer. In one or more ofthe foregoing and following embodiments, a part of the main layer isdisposed between the first membrane and the support frame. In one ormore of the foregoing and following embodiments, the pellicle furtherincludes a protection layer disposed over both sides of the firstmembrane. In one or more of the foregoing and following embodiments, theprotection layer includes at least one selected from the groupconsisting of HfO₂, Al₂O₃, ZrO₂, Y₂O₃, and La₂O₃. In one or more of theforegoing and following embodiments, the protection layer includes atleast one selected from the group consisting of B₄C, YN, Si₃N₄, BN, NbN,RuNb, YF₃, TiN, and ZrN. In one or more of the foregoing and followingembodiments, the protection layer includes a metal layer made of atleast one selected from the group consisting of Ru, Nb, Y, Sc, Ni, Mo,W, Pt, and Bi. In one or more of the foregoing and followingembodiments, a thickness of the protection layer is in a range from 0.1nm to 5 nm. In one or more of the foregoing and following embodiments,the protection layer is also formed to cover the plurality of nanotubesof the main layer. In one or more of the foregoing and followingembodiments, the plurality of nanotubes include a plurality of firstnanotubes and a plurality of second nanotubes different from theplurality of first nanotubes. In one or more of the foregoing andfollowing embodiments, the plurality of first nanotubes are single wallnanotubes and the plurality of second nanotubes are multiwall nanotubes.In one or more of the foregoing and following embodiments, the pluralityof first nanotubes are made of a same material as the plurality ofsecond nanotubes. In one or more of the foregoing and followingembodiments, the plurality of first nanotubes are made of a differentmaterial than the plurality of second nanotubes. In one or more of theforegoing and following embodiments, each of the plurality of firstnanotubes and the plurality of second nanotubes are one or more selectedfrom the group consisting of carbon nanotubes, boron nitride nanotubes,MoS₂ nanotubes, MoSe₂ nanotubes, WS₂ nanotubes and WSe₂ nanotubes. Inone or more of the foregoing and following embodiments, both theplurality of first nanotubes and the plurality of second nanotubes aresingle wall nanotubes. In one or more of the foregoing and followingembodiments, both the plurality of first nanotubes and the plurality ofsecond nanotubes are multiwall nanotubes. In one or more of theforegoing and following embodiments, the plurality of first nanotubesare single wall nanotubes and the plurality of second nanotubes aremultiwall nanotubes. In one or more of the foregoing and followingembodiments, the main layer further includes a plurality of flakescomprising two-dimensional material in which one or more two-dimensionallayers are stacked. In one or more of the foregoing and followingembodiments, the two-dimensional material includes at least one selectedfrom the group consisting of boron nitride (BN), graphene, MoS₂, MoSe₂,WS₂, and WSe₂. In one or more of the foregoing and followingembodiments, a size of each of the plurality of flakes is in a rangefrom 100 nm² to 100 μm². In one or more of the foregoing and followingembodiments, a thickness of each of the plurality of flakes is in arange from 0.3 nm to 3 nm. In one or more of the foregoing and followingembodiments, a number of the one or more two-dimensional layers of eachof the plurality of flakes is 1 to 20.

In accordance with another aspect of the present disclosure, in a methodof manufacturing a pellicle for an extreme ultraviolet (EUV) reflectivemask, a nanotube layer is formed over a support substrate, a first coverlayer is formed over the nanotube layer, a pellicle frame is attachedover the first cover layer, the nanotube layer and the first cover layerare cut to form a cut pellicle membrane, a second layer is formed tofully encapsulate the nanotube layer of the cut pellicle membrane bysealing with the first layer of the cut pellicle membrane, and aprotection layer is formed over the first cover layer, the second coverlayer and a pellicle frame. In one or more of the foregoing andfollowing embodiments, at least one of the first cover layer or thesecond cover layer includes a two-dimensional material in which one ormore two-dimensional layers are stacked. In one or more of the foregoingand following embodiments, the first cover layer includes a firsttwo-dimensional material and the second cover layer includes a secondtwo-dimensional material. In one or more of the foregoing and followingembodiments, each of the first and second two-dimensional materialsincludes at least one selected from the group consisting of boronnitride (BN), graphene, MoS₂, MoSe₂, WS₂, and WSe₂. In one or more ofthe foregoing and following embodiments, the first two-dimensionalmaterial is different from the second two-dimensional material. In oneor more of the foregoing and following embodiments, a thickness of eachof the first cover layer and the second cover layer is in a range from0.3 nm to 3 nm. In one or more of the foregoing and followingembodiments, a number of the one or more two-dimensional layers of eachof the first and second two-dimensional materials is 1 to 20. In one ormore of the foregoing and following embodiments, the protection layerincludes at least one selected from the group consisting of HfO₂, Al₂O₃,ZrO₂, Y₂O₃, and La₂O₃. In one or more of the foregoing and followingembodiments, the protection layer includes at least one selected fromthe group consisting of B₄C, YN, Si₃N₄, BN, NbN, RuNb, YF₃, TiN, andZrN. In one or more of the foregoing and following embodiments, theprotection layer includes a metal layer made of at least one selectedfrom the group consisting of Ru, Nb, Y, Sc, Ni, Mo, W, Pt, and Bi. Inone or more of the foregoing and following embodiments, a thickness ofthe protection layer is in a range from 0.1 nm to 5 nm. In one or moreof the foregoing and following embodiments, the nanotube layer includesa plurality of nanotubes having a diameter in a range from 0.5 nm to 20nm. In one or more of the foregoing and following embodiments, theplurality of nanotubes include a plurality of first nanotubes and aplurality of second nanotubes different from the plurality of firstnanotubes. In one or more of the foregoing and following embodiments, atleast one of the first layer or the second layer includes atwo-dimensional material in which one or more two-dimensional layers arestacked. In one or more of the foregoing and following embodiments, theplurality of first nanotubes are single wall nanotubes and the pluralityof second nanotubes are multiwall nanotubes. In one or more of theforegoing and following embodiments, the plurality of first nanotubesare made of a same material as the plurality of second nanotubes. In oneor more of the foregoing and following embodiments, the plurality offirst nanotubes are made of a different material than the plurality ofsecond nanotubes. In one or more of the foregoing and followingembodiments, each of the plurality of first nanotubes and the pluralityof second nanotubes are one or more selected from the group consistingof carbon nanotubes, boron nitride nanotubes, MoS₂ nanotubes, MoSe₂nanotubes, WS₂ nanotubes and WSe₂ nanotubes. In one or more of theforegoing and following embodiments, both the plurality of firstnanotubes and the plurality of second nanotubes are single wallnanotubes. In one or more of the foregoing and following embodiments,both the plurality of first nanotubes and the plurality of secondnanotubes are multiwall nanotubes. In one or more of the foregoing andfollowing embodiments, the plurality of first nanotubes are single wallnanotubes and the plurality of second nanotubes are multiwall nanotubes.In one or more of the foregoing and following embodiments, the nanotubelayer includes a plurality of nanotubes and a plurality of flakescomprising two-dimensional material in which one or more two-dimensionallayers are stacked. In one or more of the foregoing and followingembodiments, the two-dimensional material includes at least one selectedfrom the group consisting of boron nitride (BN), graphene, MoS₂, MoSe₂,WS₂, and WSe₂. In one or more of the foregoing and followingembodiments, a size of each of the plurality of flakes is in a rangefrom 100 nm² to 100 m². In one or more of the foregoing and followingembodiments, a thickness of each of the plurality of flakes is in arange from 0.3 nm to 3 nm. In one or more of the foregoing and followingembodiments, a number of the one or more two-dimensional layers of eachof the plurality of flakes is 1 to 20.

In accordance with another aspect of the present disclosure, in a methodof manufacturing a EUV pellicle, a network structure of nanotubes isformed, a two-dimensional (2D) material layer is formed over the networkstructure of nanotubes, and a protection layer is formed over thenetwork structure of nanotubes. In one or more of the foregoing andfollowing embodiments, when the network structure of nanotubes isformed, a first network structure of first nanotubes is formed, and asecond network structure of second nanotubes is formed over the firstnetwork structure of first nanotubes. In one or more of the foregoingand following embodiments, the first nanotubes are different from thesecond nanotubes. In one or more of the foregoing and followingembodiments, when the network structure of nanotubes is formed,

a third network structure of 2D material flakes is formed over the firstnetwork structure of first nanotubes. In one or more of the foregoingand following embodiments, the 2D material flakes are different from thefirst nanotubes and the second nanotubes. In one or more of theforegoing and following embodiments, the third network structure of 2Dmaterial flakes is formed over the first network structure of firstnanotubes prior to forming the second network structure of secondnanotubes over the first network structure of first nanotubes. In one ormore of the foregoing and following embodiments, the forming the thirdnetwork structure of 2D material flakes over the first network structureof first nanotubes is after forming the second network structure ofsecond nanotubes over the first network structure of first nanotubes. Inone or more of the foregoing and following embodiments, forming the 2Dmaterial layer over the network structure of nanotubes is prior toforming the protection layer over the network structure of nanotubes. Inone or more of the foregoing and following embodiments, forming the 2Dmaterial layer over the network structure of nanotubes is after formingthe protection layer over the network structure of nanotubes.

In accordance with another aspect of the present disclosure, in a methodof manufacturing a EUV pellicle, nanostructures are formed, thenanostructures are dispersed into a solution, a main membrane is formedby filtering the nanostructures by a support membrane, a firsttwo-dimensional layer is formed over a first side of the main membrane,the support membrane is removed, and a second two-dimensional layer isformed over a second side of the main membrane from which the supportmembrane is removed. In one or more of the foregoing and followingembodiments, the nanostructures include nanotubes. In one or more of theforegoing and following embodiments, the nanostructures further includeflakes of one or more two-dimensional materials. In one or more of theforegoing and following embodiments, the support membrane is porous. Inone or more of the foregoing and following embodiments, a support frameis attached on the first two-dimensional layer. In one or more of theforegoing and following embodiments, a protection layer is formed overthe first two-dimensional layer, second two-dimensional layer and thesupport frame.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A pellicle for an extreme ultraviolet (EUV)reflective mask, comprising: a first layer; a second layer; and a mainlayer disposed between the first layer and second layer and including aplurality of nanotubes, wherein: at least one of the first layer or thesecond layer includes a two-dimensional material in which one or moretwo-dimensional layers are stacked.
 2. The pellicle of claim 1, whereinthe first layer includes a first two-dimensional material and the secondlayer includes a second two-dimensional material.
 3. The pellicle ofclaim 2, wherein each of the first and second two-dimensional materialsincludes at least one selected from the group consisting of boronnitride (BN), graphene, MoS₂, MoSe₂, WS₂, and WSe₂.
 4. The pellicle ofclaim 3, wherein the first two-dimensional material is different fromthe second two-dimensional material.
 5. The pellicle of claim 2, whereina thickness of each of the first layer and the second layer is in arange from 0.3 nm to 3 nm.
 6. The pellicle of claim 2, wherein a numberof the one or more two-dimensional layers of each of the first andsecond two-dimensional materials is 1 to
 20. 7. The pellicle of claim 1,wherein the first layer and the second layer are sealed to fullyencapsulate the main layer.
 8. The pellicle of claim 7, furthercomprising a protection layer disposed over the first layer and thesecond layer.
 9. The pellicle of claim 8, wherein the protection layerincludes at least one selected from the group consisting of HfO₂, Al₂O₃,ZrO₂, Y₂O₃, and La₂O₃.
 10. The pellicle of claim 8, wherein theprotection layer includes at least one selected from the groupconsisting of B₄C, YN, Si₃N₄, BN, NbN, RuNb, YF₃, TiN, and ZrN.
 11. Thepellicle of claim 8, wherein the protection layer includes a metal layermade of at least one selected from the group consisting of Ru, Nb, Y,Sc, Ni, Mo, W, Pt, and Bi.
 12. The pellicle of claim 8, wherein athickness of the protection layer is in a range from 0.1 nm to 5 nm. 13.The pellicle of claim 1, wherein a diameter of each of the plurality ofnanotubes is in a range from 0.5 nm to 20 nm.
 14. A pellicle for anextreme ultraviolet (EUV) reflective mask, comprising: a first layer; asecond layer; and a main layer disposed between the first layer andsecond layer, wherein the main layer includes a plurality of firstnanotubes and a plurality of second nanotubes different from theplurality of first nanotubes.
 15. The pellicle of claim 14, wherein theplurality of first nanotubes are single wall nanotubes and the pluralityof second nanotubes are multiwall nanotubes.
 16. The pellicle of claim15, wherein the plurality of first nanotubes are made of a same materialas the plurality of second nanotubes.
 17. The pellicle of claim 14,wherein the plurality of first nanotubes are made of a differentmaterial than the plurality of second nanotubes.
 18. The pellicle ofclaim 17, wherein both the plurality of first nanotubes and theplurality of second nanotubes are single wall nanotubes.
 19. A method ofmanufacturing a pellicle for an extreme ultraviolet (EUV) reflectivemask, comprising: forming a nanotube layer over a support substrate;forming a first cover layer over the nanotube layer; forming a pellicleframe over the first cover layer; cutting the nanotube layer and thefirst cover layer to form a cut pellicle membrane; forming a secondlayer to fully encapsulate the nanotube layer of the cut pelliclemembrane by sealing with the first layer of the cut pellicle membrane;and forming a protection layer over the first cover layer, the secondcover layer and a pellicle frame.
 20. The method of claim 19, wherein atleast one of the first cover layer or the second cover layer includes atwo-dimensional material in which one or more two-dimensional layers arestacked.